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Introduction to Cancer
Published in David E. Thurston, Ilona Pysz, Chemistry and Pharmacology of Anticancer Drugs, 2021
Neutrons (which are particles rather than γ- or X-rays) are also used in cancer therapy (see Chapter 10). For example, a process known as high linear energy transfer has been developed to kill hypoxic cells by irradiating the tumor with neutrons that then decay to α-particles, the latter causing cellular damage in an oxygen-independent manner. A more sophisticated treatment known as boron neutron capture therapy involves administration of a boron-10 (10B)–enriched delivery agent that is taken up selectively by the tumor. The target area is then irradiated with low energy neutrons that are captured by the 10B atoms, thus leading to a reaction that produces α–particles (4He) and lithium-7 (7Li) ions that destroy the tumor tissue.
Polymer Gel Dosimetry
Published in Ben Mijnheer, Clinical 3D Dosimetry in Modern Radiation Therapy, 2017
In boron neutron capture therapy (BNCT), it is assumed that boron-10 accumulates in the tumor after administration of a tumor-specific boron carrier. After redistribution of the carrier, the patient is irradiated with epithermal neutrons. A nuclear reaction of the boron-10 with the neutrons leads to the formation of 7Li, an alpha particle and gamma radiation. Although the irradiation with epithermal neutrons results in background radiation, the localized radiation effect of the short-range alpha and 7Li-particles leads to a significant therapeutic gain. An increase in dose has been reported in a PAG dosimeter doped with boron as compared to an undoped PAG dosimeter after irradiation with epithermal neutrons (Farajollahi et al., 2000), illustrating the potential of polymer gel dosimetry. However, more studies are needed to convert the NMR R2-response to dose.
Dendritic Nanostructures for Cancer Therapy
Published in Mansoor M. Amiji, Nanotechnology for Cancer Therapy, 2006
Ashootosh V. Ambade, Elamprakash N. Savariar, S. (Thai) Thayumanavan
Neutron capture therapy (NCT) is another promising technique for treatment of cancer.22 It is based on the nuclear reaction that occurs when a stable isotope, for example, boron 10B, is irradiated with low energy or thermal neutrons to produce high-energy alpha particles (4He nuclei) and 7Li ions. The combined path length of these two particles is about 12 μm that is close to the diameter of a cell. Therefore, if the tumor cells can be supplied with a high concentration of 10B atoms, the effect of the radiation will be limited to tumor cells, and the normal cells may be spared. This is particularly important in cancer therapy where prevention of indiscriminate destruction of healthy cells is a challenge. 157Gd is another isotope of interest because of its large neutron capture cross section. Success of the above two therapies depends on localizing sufficient concentration of the photosensitizer or radioactive material in the tumor cells while having negligible accumulation in the healthy cells.
Research progress on therapeutic targeting of quiescent cancer cells
Published in Artificial Cells, Nanomedicine, and Biotechnology, 2019
Jinhua Zhang, Jing Si, Lu Gan, Cuixia Di, Yi Xie, Chao Sun, Hongyan Li, Menghuan Guo, Hong Zhang
Boron neutron capture therapy (BNCT) is a novel targeted radiotherapy that selectively kills tumor cells. After introduction into the human body, Boron (10B) is enriched in tumor cells and reacts with neutrons. The reaction generates high LET α particles (4He) and recoiling 7Li nuclei, which result in the induction of DSBs with strong biological effectiveness. Since the path lengths of these particles are almost equal to cell diameter size, only 10B-containing cancer cells are theoretically destroyed without causing serious radiation injury to surrounding normal tissue [92,93]. The cellular distribution of 10B from L-para-boronophenylalanine-10B (BPA) is believed to be largely dependent on the capability of the cells to take up 10B whereas that from sodium mercaptoundecahydrododecaborate-10B (BSH) mainly relies on drug diffusion [11]. Importantly, the use of a 10B-carrier in BNCT, especially BPA, not only effectively eliminates hypoxia and quiescent cells but also kills oxygenated and proliferative cells [11,94].
Usefulness of combination with both continuous administration of hypoxic cytotoxin and mild temperature hyperthermia in boron neutron capture therapy in terms of local tumor response and lung metastatic potential
Published in International Journal of Radiation Biology, 2019
Shin-ichiro Masunaga, Yoshinori Sakurai, Hiroki Tanaka, Takushi Takata, Minoru Suzuki, Yu Sanada, Keizo Tano, Akira Maruhashi, Koji Ono
A neutron capture reaction in boron [10B(n,α)7Li] is, in principle, very effective in destroying tumors, provided that a sufficient amount of 10B can be accumulated in the target tumor and a sufficient number of very-low-energy thermal neutrons can be delivered. The two particles generated in this reaction have a high linear energy transfer (LET) and have a range of roughly the diameter of one or two tumor cells. It is theoretically possible to kill tumor cells without affecting adjacent normal cells if 10B atoms can be selectively accumulated in the interstitial space of tumor tissue and/or intracellular space of tumor cells. Thus, successful boron neutron capture therapy (BNCT) requires the selective delivery of large amounts of 10B to tumor cells (Mirzaei HR et al. 2016; Barth et al. 2018a).
Effect of a change in reactor power on response of murine solid tumors in vivo, referring to impact on quiescent tumor cell population
Published in International Journal of Radiation Biology, 2019
Shin-ichiro Masunaga, Yoshinori Sakurai, Hiroki Tanaka, Takushi Takata, Minoru Suzuki, Yu Sanada, Keizo Tano, Akira Maruhashi, Koji Ono
A neutron capture reaction in boron [10B(n, α)7Li] is, in principle, very effective in destroying tumors, provided that a sufficient amount of 10B can be accumulated in the target tumor and a sufficient number of very-low-energy thermal neutrons can be delivered there. The two particles generated in this reaction have a high linear energy transfer (LET) and have a range of roughly the diameter of one or two tumor cells. It is theoretically possible to kill tumor cells without affecting adjacent healthy cells if 10B atoms can be selectively accumulated in the interstitial space of tumor tissue and/or intracellular space of tumor cells. Thus, successful boron neutron capture therapy (BNCT) requires the selective delivery of large amounts of 10B to malignant cells (Barth et al. 2012).